Ruby on Gaming

Well, as far as I know (not being in the game development industry myself), practically every single 3D action shooter is implemented with a bunch of core libraries written in C, C++ or assembly language and the game logic is written with a scripting language like Python or Lua.

In other words, what needs to be blazing fast is implemented with something that can get really close to the hardware but everything else is implemented in a language that's easy to write, easy to read, and easy to change.

But, again, this is coming from someone who's only observed the game industry from a distance.